1 //===-- Operator.cpp - Implement the LLVM operators -----------------------===// 2 // 3 // Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions. 4 // See https://llvm.org/LICENSE.txt for license information. 5 // SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception 6 // 7 //===----------------------------------------------------------------------===// 8 // 9 // This file implements the non-inline methods for the LLVM Operator classes. 10 // 11 //===----------------------------------------------------------------------===// 12 13 #include "llvm/IR/Operator.h" 14 #include "llvm/IR/DataLayout.h" 15 #include "llvm/IR/GetElementPtrTypeIterator.h" 16 #include "llvm/IR/Instructions.h" 17 18 #include "ConstantsContext.h" 19 20 namespace llvm { 21 bool Operator::hasPoisonGeneratingFlags() const { 22 switch (getOpcode()) { 23 case Instruction::Add: 24 case Instruction::Sub: 25 case Instruction::Mul: 26 case Instruction::Shl: { 27 auto *OBO = cast<OverflowingBinaryOperator>(this); 28 return OBO->hasNoUnsignedWrap() || OBO->hasNoSignedWrap(); 29 } 30 case Instruction::Trunc: { 31 if (auto *TI = dyn_cast<TruncInst>(this)) 32 return TI->hasNoUnsignedWrap() || TI->hasNoSignedWrap(); 33 return false; 34 } 35 case Instruction::UDiv: 36 case Instruction::SDiv: 37 case Instruction::AShr: 38 case Instruction::LShr: 39 return cast<PossiblyExactOperator>(this)->isExact(); 40 case Instruction::Or: 41 return cast<PossiblyDisjointInst>(this)->isDisjoint(); 42 case Instruction::GetElementPtr: { 43 auto *GEP = cast<GEPOperator>(this); 44 // Note: inrange exists on constexpr only 45 return GEP->getNoWrapFlags() != GEPNoWrapFlags::none() || 46 GEP->getInRange() != std::nullopt; 47 } 48 case Instruction::UIToFP: 49 case Instruction::ZExt: 50 if (auto *NNI = dyn_cast<PossiblyNonNegInst>(this)) 51 return NNI->hasNonNeg(); 52 return false; 53 case Instruction::ICmp: 54 return cast<ICmpInst>(this)->hasSameSign(); 55 default: 56 if (const auto *FP = dyn_cast<FPMathOperator>(this)) 57 return FP->hasNoNaNs() || FP->hasNoInfs(); 58 return false; 59 } 60 } 61 62 bool Operator::hasPoisonGeneratingAnnotations() const { 63 if (hasPoisonGeneratingFlags()) 64 return true; 65 auto *I = dyn_cast<Instruction>(this); 66 return I && (I->hasPoisonGeneratingReturnAttributes() || 67 I->hasPoisonGeneratingMetadata()); 68 } 69 70 Type *GEPOperator::getSourceElementType() const { 71 if (auto *I = dyn_cast<GetElementPtrInst>(this)) 72 return I->getSourceElementType(); 73 return cast<GetElementPtrConstantExpr>(this)->getSourceElementType(); 74 } 75 76 Type *GEPOperator::getResultElementType() const { 77 if (auto *I = dyn_cast<GetElementPtrInst>(this)) 78 return I->getResultElementType(); 79 return cast<GetElementPtrConstantExpr>(this)->getResultElementType(); 80 } 81 82 std::optional<ConstantRange> GEPOperator::getInRange() const { 83 if (auto *CE = dyn_cast<GetElementPtrConstantExpr>(this)) 84 return CE->getInRange(); 85 return std::nullopt; 86 } 87 88 Align GEPOperator::getMaxPreservedAlignment(const DataLayout &DL) const { 89 /// compute the worse possible offset for every level of the GEP et accumulate 90 /// the minimum alignment into Result. 91 92 Align Result = Align(llvm::Value::MaximumAlignment); 93 for (gep_type_iterator GTI = gep_type_begin(this), GTE = gep_type_end(this); 94 GTI != GTE; ++GTI) { 95 uint64_t Offset; 96 ConstantInt *OpC = dyn_cast<ConstantInt>(GTI.getOperand()); 97 98 if (StructType *STy = GTI.getStructTypeOrNull()) { 99 const StructLayout *SL = DL.getStructLayout(STy); 100 Offset = SL->getElementOffset(OpC->getZExtValue()); 101 } else { 102 assert(GTI.isSequential() && "should be sequencial"); 103 /// If the index isn't known, we take 1 because it is the index that will 104 /// give the worse alignment of the offset. 105 const uint64_t ElemCount = OpC ? OpC->getZExtValue() : 1; 106 Offset = GTI.getSequentialElementStride(DL) * ElemCount; 107 } 108 Result = Align(MinAlign(Offset, Result.value())); 109 } 110 return Result; 111 } 112 113 bool GEPOperator::accumulateConstantOffset( 114 const DataLayout &DL, APInt &Offset, 115 function_ref<bool(Value &, APInt &)> ExternalAnalysis) const { 116 assert(Offset.getBitWidth() == 117 DL.getIndexSizeInBits(getPointerAddressSpace()) && 118 "The offset bit width does not match DL specification."); 119 SmallVector<const Value *> Index(llvm::drop_begin(operand_values())); 120 return GEPOperator::accumulateConstantOffset(getSourceElementType(), Index, 121 DL, Offset, ExternalAnalysis); 122 } 123 124 bool GEPOperator::accumulateConstantOffset( 125 Type *SourceType, ArrayRef<const Value *> Index, const DataLayout &DL, 126 APInt &Offset, function_ref<bool(Value &, APInt &)> ExternalAnalysis) { 127 // Fast path for canonical getelementptr i8 form. 128 if (SourceType->isIntegerTy(8) && !ExternalAnalysis) { 129 if (auto *CI = dyn_cast<ConstantInt>(Index.front())) { 130 Offset += CI->getValue().sextOrTrunc(Offset.getBitWidth()); 131 return true; 132 } 133 return false; 134 } 135 136 bool UsedExternalAnalysis = false; 137 auto AccumulateOffset = [&](APInt Index, uint64_t Size) -> bool { 138 Index = Index.sextOrTrunc(Offset.getBitWidth()); 139 // Truncate if type size exceeds index space. 140 APInt IndexedSize(Offset.getBitWidth(), Size, /*isSigned=*/false, 141 /*implcitTrunc=*/true); 142 // For array or vector indices, scale the index by the size of the type. 143 if (!UsedExternalAnalysis) { 144 Offset += Index * IndexedSize; 145 } else { 146 // External Analysis can return a result higher/lower than the value 147 // represents. We need to detect overflow/underflow. 148 bool Overflow = false; 149 APInt OffsetPlus = Index.smul_ov(IndexedSize, Overflow); 150 if (Overflow) 151 return false; 152 Offset = Offset.sadd_ov(OffsetPlus, Overflow); 153 if (Overflow) 154 return false; 155 } 156 return true; 157 }; 158 auto begin = generic_gep_type_iterator<decltype(Index.begin())>::begin( 159 SourceType, Index.begin()); 160 auto end = generic_gep_type_iterator<decltype(Index.end())>::end(Index.end()); 161 for (auto GTI = begin, GTE = end; GTI != GTE; ++GTI) { 162 // Scalable vectors are multiplied by a runtime constant. 163 bool ScalableType = GTI.getIndexedType()->isScalableTy(); 164 165 Value *V = GTI.getOperand(); 166 StructType *STy = GTI.getStructTypeOrNull(); 167 // Handle ConstantInt if possible. 168 if (auto ConstOffset = dyn_cast<ConstantInt>(V)) { 169 if (ConstOffset->isZero()) 170 continue; 171 // if the type is scalable and the constant is not zero (vscale * n * 0 = 172 // 0) bailout. 173 if (ScalableType) 174 return false; 175 // Handle a struct index, which adds its field offset to the pointer. 176 if (STy) { 177 unsigned ElementIdx = ConstOffset->getZExtValue(); 178 const StructLayout *SL = DL.getStructLayout(STy); 179 // Element offset is in bytes. 180 if (!AccumulateOffset( 181 APInt(Offset.getBitWidth(), SL->getElementOffset(ElementIdx)), 182 1)) 183 return false; 184 continue; 185 } 186 if (!AccumulateOffset(ConstOffset->getValue(), 187 GTI.getSequentialElementStride(DL))) 188 return false; 189 continue; 190 } 191 192 // The operand is not constant, check if an external analysis was provided. 193 // External analsis is not applicable to a struct type. 194 if (!ExternalAnalysis || STy || ScalableType) 195 return false; 196 APInt AnalysisIndex; 197 if (!ExternalAnalysis(*V, AnalysisIndex)) 198 return false; 199 UsedExternalAnalysis = true; 200 if (!AccumulateOffset(AnalysisIndex, GTI.getSequentialElementStride(DL))) 201 return false; 202 } 203 return true; 204 } 205 206 bool GEPOperator::collectOffset( 207 const DataLayout &DL, unsigned BitWidth, 208 SmallMapVector<Value *, APInt, 4> &VariableOffsets, 209 APInt &ConstantOffset) const { 210 assert(BitWidth == DL.getIndexSizeInBits(getPointerAddressSpace()) && 211 "The offset bit width does not match DL specification."); 212 213 auto CollectConstantOffset = [&](APInt Index, uint64_t Size) { 214 Index = Index.sextOrTrunc(BitWidth); 215 // Truncate if type size exceeds index space. 216 APInt IndexedSize(BitWidth, Size, /*isSigned=*/false, 217 /*implcitTrunc=*/true); 218 ConstantOffset += Index * IndexedSize; 219 }; 220 221 for (gep_type_iterator GTI = gep_type_begin(this), GTE = gep_type_end(this); 222 GTI != GTE; ++GTI) { 223 // Scalable vectors are multiplied by a runtime constant. 224 bool ScalableType = GTI.getIndexedType()->isScalableTy(); 225 226 Value *V = GTI.getOperand(); 227 StructType *STy = GTI.getStructTypeOrNull(); 228 // Handle ConstantInt if possible. 229 if (auto ConstOffset = dyn_cast<ConstantInt>(V)) { 230 if (ConstOffset->isZero()) 231 continue; 232 // If the type is scalable and the constant is not zero (vscale * n * 0 = 233 // 0) bailout. 234 // TODO: If the runtime value is accessible at any point before DWARF 235 // emission, then we could potentially keep a forward reference to it 236 // in the debug value to be filled in later. 237 if (ScalableType) 238 return false; 239 // Handle a struct index, which adds its field offset to the pointer. 240 if (STy) { 241 unsigned ElementIdx = ConstOffset->getZExtValue(); 242 const StructLayout *SL = DL.getStructLayout(STy); 243 // Element offset is in bytes. 244 CollectConstantOffset(APInt(BitWidth, SL->getElementOffset(ElementIdx)), 245 1); 246 continue; 247 } 248 CollectConstantOffset(ConstOffset->getValue(), 249 GTI.getSequentialElementStride(DL)); 250 continue; 251 } 252 253 if (STy || ScalableType) 254 return false; 255 // Truncate if type size exceeds index space. 256 APInt IndexedSize(BitWidth, GTI.getSequentialElementStride(DL), 257 /*isSigned=*/false, /*implicitTrunc=*/true); 258 // Insert an initial offset of 0 for V iff none exists already, then 259 // increment the offset by IndexedSize. 260 if (!IndexedSize.isZero()) { 261 auto *It = VariableOffsets.insert({V, APInt(BitWidth, 0)}).first; 262 It->second += IndexedSize; 263 } 264 } 265 return true; 266 } 267 268 void FastMathFlags::print(raw_ostream &O) const { 269 if (all()) 270 O << " fast"; 271 else { 272 if (allowReassoc()) 273 O << " reassoc"; 274 if (noNaNs()) 275 O << " nnan"; 276 if (noInfs()) 277 O << " ninf"; 278 if (noSignedZeros()) 279 O << " nsz"; 280 if (allowReciprocal()) 281 O << " arcp"; 282 if (allowContract()) 283 O << " contract"; 284 if (approxFunc()) 285 O << " afn"; 286 } 287 } 288 } // namespace llvm 289